Ordering Recommendation

Provides a calculated value for free testosterone concentration using total testosterone measured by immunoassay. Use to evaluate hypogonadism in cisgender males with a total testosterone concentration at the lower limit of normal. May be used to evaluate testosterone status in individuals with protein-binding abnormalities or to monitor testosterone hormone therapies. Not recommended when low testosterone concentrations, such as those found in children and cisgender females, are expected. For these individuals, testing by mass spectrometry is recommended; refer to Testosterone, Free and Total, Includes Sex Hormone-Binding Globulin (Adult Females, Children, or Individuals on Testosterone-Suppressing Hormone Therapy) (0081056).

Mnemonic

FREE T

Methodology

Quantitative Electrochemiluminescent Immunoassay
The concentration of free testosterone is derived from a mathematical expression based on the constant for the binding of testosterone to sex hormone binding globulin.

Performed

Sun-Sat

Reported

Within 24 hours

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

Collect specimen between 6-10 a.m.

Collect

Serum separator tube or green (lithium heparin).

Specimen Preparation

Separate serum or plasma from cells immediately after collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.6 mL)

Storage/Transport Temperature

Refrigerated.

Unacceptable Conditions

EDTA plasma.

Remarks
Stability

After separation from cells: Ambient: 48 hours; Refrigerated: 1 week; Frozen: 2 months

Reference Interval

Test Number
Components
Reference Interval
  Testosterone, Free Calculation
Age Male (pg/mL)
14-15 years 3-138
16-17 years 38-173
18 years and older 47-244
Tanner Stage IV 35-169
Tanner Stage V 41-239

  Testosterone, Percentage Free
Age Male (%)
18 years and older 1.6-2.9

  Testosterone by Immunoassay
Age Male (ng/dL)
14-15 years 33-585
16-17 years 185-886
18-39 years 300-1080
40-59 years 300-890
60 years and older 300-720
Tanner Stage IV 165-854
Tanner Stage V 194-783

  Sex Hormone Binding Globulin
Age
Male (nmol/L)
Female (nmol/L)
1-30 days 13-85 14-60
31-364 days 70-250 60-215
1-3 years 50-180 60-190
4-6 years 45-175 55-170
7-9 years 28-190 35-170
10-12 years 23-160 17-155
13-15 years 13-140 11-120
16-17 years 10-60 19-145
18-49 years 17-56 25-122
50 years and older 19-76 17-125
Tanner Stage I 26-186 30-173
Tanner Stage II 22-169 16-127
Tanner Stage III 13-104 12-98
Tanner Stage IV 11-60 14-151
Tanner Stage V 11-71 23-165

Interpretive Data

Free testosterone concentration is calculated using total testosterone (measured by immunoassay) and the binding constant of testosterone and sex hormone-binding globulin (SHBG). Testosterone immunoassays are both imprecise and inaccurate at low testosterone concentrations, such as those found in children and cisgender females. For these individuals, testing by mass spectrometry is recommended; refer to Testosterone, Free and Total, Includes Sex Hormone-Binding Globulin (Adult Females, Children, or Individuals on Testosterone-Suppressing Hormone Therapy) (ARUP test code 0081056).

For individuals on testosterone hormone therapy, refer to cisgender male reference intervals. No reference intervals have been established for males younger than 14 years or for cisgender females. For a complete set of all established reference intervals, refer to ltd.aruplab.com/Tests/Pub/0070109.

Compliance Category

FDA

Note

Hotline History

N/A

CPT Codes

84402; 84403; 84270

Components

Component Test Code* Component Chart Name LOINC
0070113 Testosterone, Free Calculation 2991-8
0070114 Testosterone, Percentage Free 15432-8
0070130 Testosterone by Immunoassay 2986-8
0099375 Sex Hormone Binding Globulin 13967-5
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.

Aliases

  • Free Testosterone
  • Male testosterone testing
  • SHBG
  • Total Testosterone
Testosterone, Free and Total, Includes Sex Hormone-Binding Globulin (Adult Males or Individuals on Testosterone Hormone Therapy)